From DK PA 2001 01461 the use of own voice detection is known, as well as a number of methods for detecting own voice. These are either based on quantities that can be derived from a single microphone signal measured e.g. at one ear of the user, that is, overall level, pitch, spectral shape, spectral comparison of auto-correlation and auto-correlation of predictor coefficients, cepstral coefficients, prosodic features, modulation metrics; or based on input from a special transducer, which picks up vibrations in the ear canal caused by vocal activity. While the latter method of own voice detection is expected to be very reliable it requires a special transducer as described, which is expected to be difficult to realise. In contradiction, the former methods are readily implemented, but it has not been demonstrated or even theoretically substantiated that these methods will perform reliable own voice detection.
From U.S. publication No.: US 2003/0027600 a microphone antenna array using voice activity detection is known. The document describes a noise reducing audio receiving system, which comprises a microphone array with a plurality of microphone elements for receiving an audio signal. An array filter is connected to the microphone array for filtering noise in accordance with select filter coefficients to develop an estimate of a speech signal. A voice activity detector is employed, but no considerations concerning far-field contra near-field are employed in the determination of voice activity.
From WO 02/098169 a method is known for detecting voiced and unvoiced speech using both acoustic and non-acoustic sensors. The detection is based upon amplitude differences between microphone signals due to the presence of a source close to the microphones.
The object of this invention is to provide a method, which performs reliable own voice detection, which is mainly based on the characteristics of the sound field produced by the user's own voice. Furthermore the invention regards obtaining reliable own voice detection by combining several individual detection schemes. The method for detection of own vice can advantageously be used in hearing aids, head sets or similar communication devices.